redraw chart when table td attribute changes

[ppswang]

Hi,

This is related to issue #84
I can re-draw charts by calling highchartTable() as explained in the issue.

However, while calling the method will update the chart with changes in the TD values, it doesn't seem to update the TH attributes.

Specifically, I am updating the TH cells by adding/removing attribute "data-graph-hidden", e.g.:

x.removeAttribute("data-graph-hidden")

x.setAttribute("data-graph-hidden", "1")

and then update the chart by calling highchartTable().

It seems that I can hide a data series by setting the attribute ("data-graph-hidden"), but once the data series is hidden, I cannot bring it back by removing the attribute from the TH element.